Fix elide-integration-tests build warnings

[aklish]

Fix the following build warnings in elide-integration tests:

[WARNING] /sd/workspace/src/github.com/yahoo/elide/elide-integration-tests/src/test/java/example/models/versioned/BookV2.java:[19,1] Generating equals/hashCode implementation but without a call to superclass, even though this class does not extend java.lang.Object. If this is intentional, add '@EqualsAndHashCode(callSuper=false)' to your type.
[WARNING] /sd/workspace/src/github.com/yahoo/elide/elide-integration-tests/src/test/java/example/models/triggers/Invoice.java:[24,1] Generating equals/hashCode implementation but without a call to superclass, even though this class does not extend java.lang.Object. If this is intentional, add '@EqualsAndHashCode(callSuper=false)' to your type.
[WARNING] /sd/workspace/src/github.com/yahoo/elide/elide-integration-tests/src/test/java/com/yahoo/elide/tests/ResourceIT.java:[931,32] non-varargs call of varargs method with inexact argument type for last parameter;
  cast to com.yahoo.elide.test.jsonapi.elements.Resource for a varargs call
  cast to com.yahoo.elide.test.jsonapi.elements.Resource[] for a non-varargs call and to suppress this warning
[WARNING] /sd/workspace/src/github.com/yahoo/elide/elide-integration-tests/src/test/java/com/yahoo/elide/tests/ResourceIT.java:[1011,23] isEmptyOrNullString() in org.hamcrest.Matchers has been deprecated
[WARNING] /sd/workspace/src/github.com/yahoo/elide/elide-integration-tests/src/test/java/com/yahoo/elide/tests/ResourceIT.java:[1022,23] isEmptyOrNullString() in org.hamcrest.Matchers has been deprecated